Water-dispersible,heat-hardening interpolymers including monomeric transesters of alkoxy alkylated aminotriazine with unsaturated acid



United States Patent 3,450,660 WATER-DISPERSIBLE, HEAT-HARDENING INTER- POLYMERS INCLUDING MONOMERIC TRANS- ESTERS 0F ALKOXY ALKYLATED AMINOTRI- AZINE WITH UNSATURATED ACID Kazys Sekmakas, Chicago, Ill., assignor to De Soto, IIKL, Chicago, Ill., a cor oration of Delaware No Drawing. Filed Feb. 25, 1966, Ser. No. 529,924 Int. Cl. C08f 15/40, 27/08; C08g 37/32 US. Cl. 26029.4 11 Claims ABSTRACT OF THE DISCLOSURE Non-gelled, heat-hardening interpolymers which are dispersible in water with the aid of a base are provided by interpolymerizing monomeric transesters such as those formed by transesterifying hexamethoxy methyl melamine with monobutyl maleate. The transester is interpolymerized with an unsaturated monomer containing the hydroxy group, such as hydroxyethyl acrylate, and ethylenic monomer providing the carboxyl group, such as acrylic acid, and a portion of ethylenic monomer free of functional groups such as acrylate esters with monohydric alcohols.

The present invention is related to the copending application of myself and Frank Ragas, Ser. No. 491,049, filed Sept. 28, 1965, now United States Patent 3,396,209, granted Aug. 6, 1968.

The present invention relates to water soluble thermosetting resins including resins which are particularly adapted to be applied by electrophoretic deposition methods.

In accordance with the present development, a water soluble alkoxy alkylated triazine derivative is reacted with a monoethylenically unsaturated monocarboxylic acid to provide a monoester which is copolymerized with other monoethylenically unsaturated monomers including monomers providing hydroxy functionality and monomers providing carboxy functionality in order to provide an interpolymer which can be dispersed in water with a volatile nitrogenous base such as ammonia or an amine and which, when filmed on a substrate and baked, will thermoset to provide coatings of good properties from aqueous medium. The invention particularly contemplates electrophoretic deposition in which the complete association between the alkoxy alkylated triazine and the unsaturated acid monomer prior to copolymerization insures complete incorporation of this component into the copolymer so that only a single resin phase is available for response to the electrophoretic force to thereby insure that the resin phase will deposit uniformly with no portions thereof building up in the aqueous system which is relied upon.

As pointed out in application Ser. No. 491,049, it is.

important to form a transester with the alkoxy alkylated triazine and not a polymer of the unsaturated acid which is reacted. Similarly, it is desired to form a copolymer of the transester with other monoethylenically unsaturated monomers so as to build an acrylic-type backbone into the copolymer instead of forming a homopolymer of the unsaturated transester which would have little utility in coating processes. Accordingly, the unsaturated acid which is selected is a monoester of maleic or fumaric acids which has little tendency toward homopolymerization. In this manner, homopolymerization of the unsaturated acid during transester formation and homopolymerization of the transester which is formed are largely eliminated.

Referring first to the alkoxy alkylated triazine, this will be exemplified by hexamethoxy methyl melamine. This starting material is subjectedin accordance with the invention to very extensive modification and it must retain its solvent-soluble, non-gelled condition as well as the capacity to be brought into intimate association with water. Accordingly, the hexamethoxy methyl melamine should be essentially monomeric. Also, and for good water association, the alkylene group should be ethylene or methylene, the latter being strongly preferred and this group should be substantially completely tied up in ether form with ethanol or methanol, the latter, again, being strongly preferred.

While melamine has been referred to as a particularly preferred triazine, any polyamine and especially any triazine can be used so long as it is substantially completely alkoxy alkylated. Stated in different language, all aminotriazines can be used which contain at least two NH groups, insofar as they can be converted into the corresponding methylol compounds with formaldehyde and subsequently etherified. For reasons of economy it is desirable to use the most easily accessible products such as melamine, and also N-phenyl-melamine, benzoguanamine, acetoguanamine, formoguanamine, ammeline, 2:4- diamino-6-chloro-l:325-triazine or the like.

It should be noted that the materials which are used in accordance with the invention should be substantially free of hydroxy and amide or amino groups since these tend to interfere with the reactions which are desired in accordance with the invention.

The unsaturated acid should be monoethylenically unsaturated and it must not be one which readily homopolymerizes. It is broadly possible to use maleic, fumaric, 0r itaconic acids, since these have little tendency to form homopolymers, but each molecule of acid is capable of bonding with two molecules of the melamine ether which increases molecular weight. Accordingly, in the preferred practice of the invention, the unsaturated acid which is selected is a half ester of maleic, fumaric, or itaconic acids. Any hydrocarbon radical may be used in the ester formation, but the preferred esters are formed with alcohols containing from 1-8 carbon atoms, most preferably ethyl alcohol and butyl alcohol.

As pointed out in application Ser. No. 491,049, transesterification is important because it has been found that the transesterification reaction can proceed with the production of volatile alcohol such as methanol to provide an essentially monomeric transester. In other words, the transesterification reaction is substantially preferential and condensation of the hexamethoxy methyl melamine during the reaction is substantially excluded.

It is also preferred to insure that all of the melamine starting material is available for copolymerization and that all of the copolymerizable monomer is copolymerized with the melamine component. This requires that the hexamethoxy methyl melamine and the unsaturated acid be reacted in substantially equimolar amounts (i20% provides the most preferred form of the invention), and the reaction should be carried through to completion in order that substantially all of the melamine component is in the form of an unsaturated ester and substantially all of the unsaturated acid is eliminated from the system. In this respect, completion of the reaction is easily noted by the substantial elimination of acidity and the reaction can therefore be followed either by following acid number or, and especially when experience with the reaction is obtained, by noting the amount of alcohol removed during the transesterification reaction.

Of course, one can still obtain some of the benefits of the invention by departing from the preferred proportions noted hereinbefore. Thus, one can broadly utilize a mol 3 ratio as low as 0.5 equivalent of acid per mol of aminotriazine. Similarly, and at the sacrifice of some Water solubility, one can use up to 0.5 equivalent of acid per equivalent of alkoxy group in said aminotriazine.

The transesterification step is preferabl carried out under anhydrous conditions and preferably in the absence of inert solvents. An organic solvent medium may be employed if so desired, such as aromatic hydrocarbons or ketones. The transesterification reaction is carried out at a temperature ranging from 100 F. to 350 F. A preferred range is 200 F. to 280 F. Ordinarily, it is preferred to conduct the reaction under a reduced pressure (partial vacuum) in order to speed the removal of the volatile product of the transesterification (the alcohol corresponding to the alkoxy group).

The unsaturated melamine ester per se is a hard and brittle intermediate claimed in said application Ser. No. 491,049. Therefore, this ester is copolymerized with ethylenically unsaturated monomeric materials containing the CH =C group. By appropriately selecting the ratios of unsaturated vinyl or acrylic monomers, the resulting products may range from flexible types to very hard, brittle mar proof resinous materials, The ethylenically unsaturated monomers capable of copolymerizing with the triazine esters of the invention may be any one of a number of materials having a polymerizable CH =C group, such as vinyl toluene, styrene, ethyl acrylate, butyl acrylate, vinyl acetate, vinyl stearate, 2- ethylhexyl acrylate, and others well known to the art, especially in combinations of monomers producing hard polymers and monomers producing soft polymers.

The ethylenically unsaturated monomeric materials which are copolymerized with the unsaturated melamine ester must include materials providing hydroxyl groups. These are most usually available with the hydroxyl group being primary or secondary as illustrated by 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate, 2-hydroxy propyl butyl maleate, 2-hydroxy ethyl methacrylate, 2- hydroxy propyl methacrylate, Z-hydroxy methyl-S-norbornene, allyl alcohol, methallyl alcohol, 2-hydroxy ethyl crotonate, 2, hydroxy propyl crotonate, and crotyl alcohol.

In the preferred practice of the invention, there is pro vided a stoichiometric excess of the total of hydroxy groups and carboxyl groups in the interpolymer, in comparison with the number of methoxy groups remaining in the melamine ester. This is because the hydroxy groups are far more rapidly reactive with the methoxy group than is the methoxy group reactive with itself. If any excess of methoxy is provided and remains unreacted during the cure it tends to decrease the water and chemical resistance of the cured product.

From the standpoint of weight proportions, the methoxy methyl triazine ester may be used in an amount of from 250% by Weight of the final interpolymer, preferably in an amount of from 530%, on the same basis. These same weight proportions generally prevail with respect to the unsaturated hydroxy-providing component, so long as it is understood that the hydroxy component should be present in stoichiometric excess as previously indicated and so long as it is further understood that it is preferred that at least 20% of the interpolymer, preferably at least 30% of the interpolymer, be constituted by vinyl monomers carrying no functional groups in order to provide the desired physical properties and an appropriate cross-linked density.

It is also important that the interpolymer include a proportion of an ethylenically unsaturated material providing free carboxyl groups. These materials are illustrated by acrylic acid, methacrylic acid, crotonic acid, monobutyl maleate, itaconic acid, maleic acid, fumaric acid, and the like. Acrylic acid is especially preferred and methacrylic acid and crotonic acid are quite good. The

4 remaining acids are of lesser value. These may be used in an amount of from 130% by weight of the interpolymer, preferably from 3-15% by weight. The purpose is to provide sufficient carboxyl functionality to enable association with a nitrogenous base in order to provide an afiinity for water and enable the thermosetting interpolymers of the invention to be either dissolved or effectively dispersed in an aqueous medium.

The copolymerization reaction is a standard solution copolymerization conducted in an organic solvent in which the monomers and the polymer are soluble. From the standpoint of convenience, it is preferred to employ an organic solvent which is miscible with Water since this facilitates subsequent association of the polymer in the desired aqueous medium. In this connection, any inert organic solvent which is miscible with water may be used, these being illustrated by methyl alcohol, ethyl alcohol, isopropyl alcohol, propyl alcohol, 2-ethoxy ethanol, 2- butoxy ethanol, Z-methoxy ethanol, acetone, etc.

Chain terminating agents, such as mercaptans, may be used to exert their known effect of lowered average molecular weight.

Any free-radical generating polymerization catalyst may be used, the selection of catalyst being determined by the desired temperature of the polymerization reaction. The important point is that the agent liberate free radicals under-the conditions of polymerization so that the addition polymerization is facilitated. The class of catalysts under consideration is too well known to require extensive discussion, the examples illustrating suitable materials.

The specific nature of the nitrogenous base which is selected is not a primary "feature of the invention. In selecting the volatile base, the base is desirably of sulficient volatility to vaporize so that at least a large portion of the base will leave the film which is deposited during the operation of drying the film. Ammonia is a preferred nitrogenous base, but other volatile bases such as volatile aliphatic amines may be employed and are preferred. Volatile aliphatic amines are illustrated by monomethyl amine, dimethyl amine, diethyl amine, triethyl amine and morpholine. While volatile nitrogenous bases are preferred, non-volatile bases may, less desirably, be used such as sodium and potassium which may be employed in the form of hydroxides or alkaline salts such as carbonates.

In some instances, and as an optional feature, it is helpful to include in the aqueous phase a small proportion of water soluble organic solvent which serves as a coupling agent to improve solution clarity and to enhance film flow upon subsequent application and baking. Appropriate water soluble organic solvents for this purpose are alcohols such as ethanol, glycols such as ethylene glycol, propylene glycol and butylene glycol, glycol ethers such as 2-ethoxy ethanol and 2-butoxy ethanol as well as esters of said glycol ethers such as the acetate thereof.

The invention is illustrated in the examples which follow.

EXAMPLE 1 Preparation of hexamethoxy-methyl melamine-maleic acid half ester adduct Charge into reactor equipped with agitator, thermometer and connector to vacuum pump. Heat to 270 F. Hold for one hour. Cool to 240 F.:

Maleic anhydride (1 equivalent) grams 98 Butyl alcohol do 74 Add: Hexamethoxy methyl melamine (6 equivalents) grams 390 *5 6 Final characteristics of adduct Benzoyl peroxide parts by weight 3 Viscosity (Gardner) Z2 Z3 Add triethyl a ine and water: color (Gardnepfloldt) 2 Triethyl amine "parts by weight 57 Acid value 13,6 Water (distilled) ---d EXAMPLE 2 5 Final characteristics of polymer Preparation of hydroxy-melamine polymer SQIidS 11 0 The following example demonstrates the preparation of Vlscoslty (Gardner) C a water soluble hydroxy-melamine interpolymer, contain- Color ('Gardner'Holdt) 1 ing reactive methoxy groups in the polymer chain. 10 Add triethyl amine to adjust pH to 7.2. Add water to Charge into areactor equipped with an agitator, thermomdilute to 10-20% solids, when used for electrophoretic eter, reflux condenser, addition funnel and nitrogen ep sit n. inlet tube. Heat to 190 F.: EXAMPLE 4 IFOPrOPaHOI "Parts by Welght" A water soluble acrylic-hydroxy-melamine interpoly- Premlx monomers solvent catalyst add to mer is prepared having the following ratios of reactive actor over two hour period. Hold [for two hours at groups: l90195 F Isopropanol parts by weight 100 Y Y equfvalents Adduct of Example 1 do 300 MethOXY eqqlvalents Igobutyl acrylate do 210 Carboxy equlvalents Hydroxy ethyl acrylate do 340 H to 190 F; y acid 50 Isopropanol "parts by weight 400 yl yl 2100 Premix and add to reactor over 2 hours at 190195 F. z y PeI'OXidB 10 Hold for two hours: Add catalyst and hold for three hours to complete monoduct of Example 1 parts by Weight 300 mer conversion. Cool to 140 F.: E h 1 acrylate d 410 Ben yl PBTOXide P y g 3 Z-hydroxy ethyl acrylate do 340 Add triethyl amine and water: A li id d 50 T y amine 57 Isopropanol do 100 Water (distilled) 570 Benzoyl peroxide do 10 Final characteristics of polymer Add catalyst and hold for complete monomer conversion: Solids (percent) Benzoyl peroxide "par y w g Viscosity (Gardner) Q-R w and add: Color (Gardner-Holdt) 2 Tnethyl Q 57 When used for electrophoretic deposition, 'add triethyl Water (dlstllled) 570 amine to adjust pH to 7.1-7.2. Add water to dilute to Final characteristics 10-20% solids. Ratio of water to isopropanol: 9* parts Solids (percent) 49.1 water to 1 part isopropanol. Viscosity (Gardner) T-U EXAMPLE 3 40 Color (Gardner) 1-2 Preparation of hydroxy polymer The inter-polymer is diluted to 10% resin solids using The f ll i example demonstrates h preparation distilled Waterand exhibits excellent electrophoretic depof water soluble hydroxy polymers, containing no melaosltlon P p mme the Polymer cham- Evaluation of water-soluble hydroxy polymers for use in Charge into a reactor equipped with an agitator, thermomelectrophoretic coatings 2 :52; i 3 gg ig gdo gi funnel and mtrogm The resin is reduced to 1 solids using water. The pH lsopmp'anol "Parts by weight" 400 is ad usted to 7.1 using triethyl amine. The resln solu- Premix monomers, solvent and catalyst. Add to reactor Is qharged i i i beaker eqmppefl Wnh i over two hour period (190 F.) Hold for two hours at netlc i T Panels a Immersed 9 190495 R: the resin solution. Resin film 1S deposited using milllllsopropanol parts by weight ampere current per each square centimeter. 1 )ur1ng the lsobutyl ig "do 210 deposition, the voltage is increased gradually 111 order to Hydroxy ethyl aclfylate 340 55 lieep constant amperage. The equipment used 1s described Acrylic acid 50 1n deta1l III Electrodeposrtron: Theory and Practice, Of- Ethyl acrylate "don" 200 ficial Digest, February 1965, pp. 114-115. Benzoyl peroxide do 10 Total deposition time: seconds Add catalyst and hold for 3 hours at 190 F. for com- Thickness of deposited film: 0.8 mil plete conversion. Cool to F.: Characteristics of film: smooth and even Hydroxy Polymer of Example 3 Cold Blended with hexamethoxy Hydroxy Polymer methyl melamine in an amount Hydroxy-Melamine of Example 3 providing the same ratio of Interpolymer of (Containing no melamine to hydroxy as used Example 2 Melamine) in Example 4 Film deposition properties Very good Very good Very good. Baking time 20 minut 20 minutes 20 minutes. Temperature.-." 0 F 350 F Toluol Resistance Excellent Very poor (film dissolves) Poor Sodium Hydroxide (1% Solution): Dry Film Thickness (mils) Film removed in 5 minutes. Film removed in 15 minutes.

The invention is defined in the claims which follow.

I claim:

1. A non-gelled, heat-hardening interpolymer adapted to be dispersed or dissolved in water with a base and comprising interpolymerized units of:

(A) from 250% by weight of an essentially monomeric transester of substantially completely alkoxy alkylated aminotriazine containing at least two NH groups with monoethylenically unsaturated carboxylic acid from the group of maleic acid, fumaric acid, itaconic acid, and half esters thereof with monohydric alcohols, the alkoxy and alkylene groups of said alkoxy alkylated aminotriazine each containing 1 or 2 carbon atoms;

(B) from 25()% by Weight of ethylenically unsaturated monomer providing the hydroxyl group;

(C) from 130% by weight of ethylenically unsaturated monomer providing the carboxyl group; and

(D) at least 20% by weight of ethylenically unsaturated material containing the CHFC group and otherwise free of functional groups.

2. An interpolymer as recited in claim 1 in which said alkoxy alkylated aminotriazine is hexamethoxy methyl melamine.

3. An interpolymer as recited in claim 1 in which said monomeric transester is provided by reacting one molar proportion of said acid per mole of said aminotriazine to provide a monoester.

4. An interpolymer as recited in claim 3 in which said acid is a monoester of dicarboxylic acid selected from the group consisting of maleic acid and fumaric acid with a monohydric alcohol containing from 1-8 carbon atoms.

5. An interpolymer as recited in claim 1 in which said ethylenically unsaturated monomer providing hydroxy groups is selected from the group consisting of 2-hydroxy ethyl acrylate, 2-hydroxy propyl acrylate, 2-hydroxy propyl butyl maleate, 2-hydroxy ethyl methacrylate, 2- hydroXy propyl methacrylate, 2-hydroxy methyl-S-norbornene, allyl alcohol, methallyl alcohol, 2-hydroxy ethyl crotonate, 2-hydroxy propyl crotonate, and crotyl alcohol.

6. An interpolymer as recited in claim 1 in which said ethylenically unsaturated monomer providing the carboxyl group is selected from the group consisting of acrylic acid, methacrylic acid and crotonic acid.

7. An interpolymer as recited in claim 1 in which the total of the hydroxyl groups and the carboxyl groups contained therein are in stoichiometric excess with respect to the alkoxyalkyl groups in said ester.

8. An interpolymer as recited in claim 1 in which said polymer is provided in solution in a water-miscible organic solvent.

9. A non-gelled, heat-hardening interpolymer adapted to be dispersed or dissolved in water with a base and comprising interpolymerized units of:

(A) from 2-50% by weight of an essentially monomeric mono transester of substantially completely methoxy methylated aminotriazine containing at least two NH groups with a half ester of an acid from the group of maleic acid, fumaric acid, and itaconic acid with monohydric alcohols;

(B) from 250% by weight of ethylenically unsaturated monomer providing the hydroxyl group;

(C) from 130% by weight of ethylenically unsaturated acid from the group of acrylic acid, methcrylic acid and crotonic acid; and

(D) at least 20% by weight of ethylenically unsaturated material containing the CHFC group and otherwise free of functional groups.

10. An aqueous medium having dispersed or dissolved therein with the aid of a base, the polymer of claim 1.

11. An aqueous medium as recited in claim 10 in which said aqueous medium comprises water-soluble organic solvent.

References Cited UNITED STATES PATENTS 2,829,119 4/1958 Dudley 26067.6 2,871,209 1/1959 Shelley 26067.6 2,885,382 5/1959 Zuppinger et al 26067.6 2,986,541 5/1961 Zuppinger et al 26067.6 3,018,265 1/1962 Tessmar 260856 3,258,339 6/1966 Adams 260-29.4 3,298,978 1/ 1967 Rutherford 260856 SAMUEL H. BLECH, Primary Examiner.

JOHN C. BLEUTGE, Assistant Examiner.

US. Cl. X.R. 

